///////////////////////////////
//  Makumba, Makumba tag library
//  Copyright (C) 2000-2003  http://www.makumba.org
//
//  This library is free software; you can redistribute it and/or
//  modify it under the terms of the GNU Lesser General Public
//  License as published by the Free Software Foundation; either
//  version 2.1 of the License, or (at your option) any later version.
//
//  This library is distributed in the hope that it will be useful,
//  but WITHOUT ANY WARRANTY; without even the implied warranty of
//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
//  Lesser General Public License for more details.
//
//  You should have received a copy of the GNU Lesser General Public
//  License along with this library; if not, write to the Free Software
//  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
//
//  -------------
//  $Id$
//  $Name$
/////////////////////////////////////

package org.makumba.commons;

import java.lang.ref.ReferenceQueue;
import java.lang.ref.SoftReference;

/**
 * A NamedResources that keeps its resources as soft references
 * 
 * @see org.makumba.commons.NamedResources
 */
public class SoftNamedResources extends NamedResources {
    private static final long serialVersionUID = 1L;

    private ReferenceQueue<NameValue> queue = new ReferenceQueue<NameValue>();

    private int diff = 0;

    public SoftNamedResources(String name, NamedResourceFactory f) {
        super(name, f);
    }

    @Override
    protected NameValue getNameValue(Object name, Object hash) {
        NameValue nv = null;
        SoftReference<?> sr = (SoftReference<?>) values.get(hash);
        if (sr == null || (nv = (NameValue) sr.get()) == null) {
            if (sr != null && nv == null) {
                diff--;
            }
            values.put(hash, new SoftReference<NameValue>(nv = new NameValue(name, hash, f), queue));
            misses++;
        } else {
            hits++;
        }
        return nv;
    }

    @Override
    public String getName() {
        return name + " (soft cache)";
    }

    @Override
    public synchronized int size() {
        while (queue.poll() != null) {
            diff++;
        }

        // sanity check
        // int diff2=0;
        // for (Object o:values.values())
        // if (((SoftReference<NameValue>) o).get() == null)
        // diff2++;
        // if(diff2!=diff)
        // throw new IllegalStateException(diff+ "<>"+diff2+" out of " +super.size());
        // end check

        return super.size() - diff;
    }
}
